Bark and ambrosia beetles on Mt. Wilhelm, Papua New Guinea

Global warming is expected to shift the distribution ranges of many
species towards higher latitudes and altitudes. This will rewire
plant-herbivore food webs as new combinations of herbivore species
encounter novel host plants. We investigated the effects of a simulated
altitudinal shift in a herbivore-host community of bark and ambrosia
beetles on fig trees in a tropical mountain forest on Mt. Wilhelm, Papua
New Guinea. We reared beetles from wood baits cut from five local Ficus
species in their natural altitudinal ranges, between 200 – 1700 masl.
Further, we transplanted baits from three of these tree species 500 m
below the limits of their natural distribution range, to simulate a mean
temperature increase of 2.7°C. Beetle species richness declined, and their
species composition changed with increasing elevation. Furthermore, while
altitude explained a large proportion of variance in beetle composition,
host tree species was more important for bark beetles than ambrosia
beetles. Beetle communities that assembled on the transplanted baits were
similar in diversity and host specificity to those on the fig trees native
to the same elevation, but also contained a number of unique species.
Overall, these results indicate that saproxylic beetles in this tropical
forest are highly resilient and flexible to the potential effects of
climate change.